Trace Al/Rb regulation stabilizes Cu-Fe5C2 active sites for ambient-pressure photothermal CO2 hydrogenation to C2-C4 olefin

Photothermal hydrogenation of CO2 offers a solar-driven route to multicarbon hydrocarbons, but controlling carbide formation and maintaining reconstructed active sites remain challenging for iron-based catalysts. Here, we develop a trace Al/Rb co-promoted CuFe2O4 catalyst that enables efficient and stable photothermal CO2 hydrogenation to light olefin under ambient pressure. The optimized catalyst achieves high C2-C4 olefin selectivity of approximately 63%, suppressing CH4 selectivity and sustaining stable photothermal-catalytic performance for 200 h. Integrated experimental characterizations and theoretical calculations reveal that the CuFe2O4 precursor undergoes reaction-induced reconstruction to form Cu-Fe5C2 interfacial structures. Trace Al/Rb promotion facilitates the formation and stabilization of reconstructed metal–carbide interfaces, with Al regulating the Fe-centered coordination environment and carbide stability, while Rb tunes the interfacial electronic structure and adsorption–hydrogenation balance. This cooperative regulation stabilizes carbide-based interfacial active sites and promotes CO2-derived C1 intermediates toward C–C coupling and C2-intermediate stabilization, thereby favoring C2-C4 olefin formation. Achieving selective photothermal CO2 hydrogenation to C2–C4 olefins under ambient pressure is challenging. This work shows that trace Al/Rb regulation stabilizes Cu-Fe5C2 interfacial active sites, enabling efficient CO2 conversion to light olefins.